I. Field of the Invention
This invention relates to locks for sliding doors or windows. It is primarily adapted for use with an application to sliding glass doors of showcases where articles to be sold are stored for display.
One well known and largely used type of showcase has a base, that supports fixed vertical sides, a vertical front and rear, and a horizontal top, largely composed of glass. The rear of the showcase is closed by movable doors located in closely adjacent vertical planes, one in front of the other. The doors move in opposite directions with their outer edges receivable in opposite outer ends of the showcase and overlap at adjacent inner edges when the doors occupy their closed positions. Each door, also usually of glass, is also movable with respect to the other to selectively open the showcase substantially one-half of its length at either end. The doors are mounted on suitable track means for movement there along to open substantially one-half of the rear wall of the showcase at either end when the two glass doors are located in substantial alignment with each other.
II. Technology Problems and Patents of Interest
The prior art has provided sliding doors of the type just described with locks that either required the doors or windows to be notched to receive locking pins or, to avoid notching the doors or windows, special angularly shaped corner engaging devices have been used to engage certain inner corners of the windows when the windows occupy their locked positions. For one reason or another, the prior art locks needed improvement. They either required weakening of the doors or windows by providing notches or recesses where the locking means engage the windows in the locked closed position, or the other devices of the prior art, which use angular members that pivot to engage a corner of each movable window, are essentially of a more complicated construction requiring more complicated actuating mechanism than desired for a lock of the type desired.
In the prior patent art, U.S. Pat. No. 1,404,297 to Hunter shows pins 12 and 13 that engage sockets 17 and 18 to lock windows shut. Drilling sockets weakens the windows so that if the windows are not in the exact positions needed for locking by engaging the pins into the sockets, glass windows are liable to chip at the vicinity of each socket.
U.S. Pat. No. 1,766,910 to Knapp discloses a lock having aligned notches 17 at the inner ends of the windows to receive pins 20 to lock the windows. Unless the notches are exactly aligned when the windows close, it becomes difficult for misaligned notches to receive said pins. Therefore, it is difficult to lock the notched windows properly.
U.S. Pat. Nos. 2,196,001 and 2,448,745 to Vanderveld disclose sliding door locks in which pivotally mounted locking members have angular fingers that engage corner portions of the glass windows to be locked into position. Complicated mechanical structures are required to ensure proper alignment of the angular members with the corners of the windows to be locked into position. These locks are relatively expensive to manufacture and require high labor costs to install.
It would be desirable to be able to provide a lock that involves using a simple pin without requiring the need for providing the glass windows or doors with sockets or notches to receive the pins. Unfortunately, when pins have to engage into sockets, it is essential that they be brought into exact alignment with the sockets. Similarly, when angular fingers engage the corners of the windows, it is also necessary that they be properly aligned both as to angle and position with respect to the closed position occupied by the window being locked. The avoidance of complicated structures to ensure proper locking of the glass which is characteristic of the prior art is an important feature of the present invention.